1. Field of the Invention
The present invention relates to molding machines used for injection-molding resin products. The present invention also relates to methods of molding resin products.
2. Description of the Related Art
A molding machine for directly molding a resin product on a base member is known. In a known direct molding process, a mold is brought to contact with a previously molded base member to define a cavity between a surface of the base produce and the mold, and a molten resin is then injected into the cavity, so that a resin product, such as a rivet, a clip and a rib, may be fixed to the base member during the injection molding process. By using the direct molding process, it is possible to mold a resin product having an intended shape at a desired position of the base member without need of change of design of a mold that is used for molding the base member. In addition, a joint member for joining two separate base members can be molded by the direct molding process, so that it is possible to join the base members at a lower cost because a management cost for a separate joint member is not necessary. As a material of the resin product, polypropylene resin having a melting point of about 220 degrees has been generally used.
In order to perform a direct molding process, there has been known a technique of using a vertical injection molding machine as disclosed in Japanese Laid-Open Patent Publication No. 2008-284759.
Unlike a generally known injection molding process, in which a resin product is molded as an individual product, a position of a part of a base member where a resin product is molded is important in the case of application of the direct molding process. Thus, it is preferable that the position of a part of the base member where the resin product is molded can be easily changed. However, with the direct molding machine incorporating the technique of a generally known injection molding machine, it requires troublesome operations for changing the molding position. FIG. 5 shows a part of a direct molding machine 9 that utilizes a vertical injection molding machine. As shown in FIG. 5, an injection-side mold 91 is directly fixed to a mount surface 921 of a mount base 92. Due to this arrangement, an injection device 93 for injecting a molten resin is necessary to be mounted to the mount base 92 from the side of a surface 922 opposite to the mount surface 921. For this reason, a hole 923 sized for receiving an injection nozzle 931 of the injection device 93 must be formed previously in the mount base 92 at a position corresponding to a desired molding position.
If it is desired to change the molding position in the direct molding machine shown in FIG. 5, the following troublesome operations are necessary to be performed. Thus, in order to change the molding position, the mold 91 and the injection device 93 are removed individually from the mount base 92. Then, the mount base 92 is removed from tie bars 94 and is replaced with another mount base having a hole for receiving the injection nozzle 931 at a different position from that of the mount base 92. Thereafter, the mold 91 and the injection device 93 are mounted to the replaced mount base.
Therefore, there has been a need in the art to enable easy change of a molding position.